1. Field of the Invention
This invention generally relates to a system and a method for supervising a vehicle-use battery.
2. Description of the Related Art
A vehicle equipped with an idle stop function is known. The idle stop function is aimed at improving fuel economy and reducing the amount of exhaust gas for internal combustion engines on vehicles. When a predetermined condition is met, the engine is stopped. When a predetermined starting condition is met, the engine is automatically restarted. An example of the idle stop function is described in Japanese Patent Application Publication No. 2004-229479.
The following situation may happen to the vehicle equipped with the idle stop function. A user temporarily stops the vehicle in the idle stop state and goes out of the vehicle, so that no person rides on the vehicle. In this case, if the user goes out of the vehicle while an electrical unit such as an air conditioner, a navigation system or an audio system is operating, the operating electrical unit consumes a battery on the vehicle, and the battery may finally run out. On the other hand, the user may feel uncomfortable if all electrical units are OFF when the user returns to the vehicle or the user is needed to operate the ignition key to restart the engine.